Nonmagnetic copper-based alloy

ABSTRACT

The present invention relates to nonmagnetic copper-based alloys applicable in the apparatus for magnetic tape recording and playback. The alloy contains 4.5 to 4.9% nickel, 4.5 to 4.9% aluminum, 2.5 to 3% manganese, 0.7 to 1% chromium and copper.

United States Patent Bobylev et a]. Y

[ 51 Mar. 21, 1972 NONMAGNETIC COPPER-BASED ALLOY Inventors: Alexei Vasilievich I Bobylev, ulitsa Arkhitektora vlasova 41; Kapitolina Arsenievna Goryacheva, ulitsa 3a, korpus l, kv. 73; Alla Vasilievna Chernikova, Otkrytoe shosse, 21 korpus 2, kv. 113, all of Moscoyv, U .S S.R.

Filed: Aug. 17, 1970 Appl. No.: 64,565

U.S.Cl ..75/153,75/l59,75/l61,

75/162 Int. Cl ..C22c 9/06, C22c 9/00 Field of Search ..75/153,159, 161,162

Primary Examiner-Charles N. Lovell Attorney-Waters, Roditi, Schwartz & Nissen 57 ABSTRACT The present invention relates to nonmagnetic copper-based alloys applicable in the apparatus for magnetic tape recording and playback. The alloy contains 4.5 to 4.9% nickel, 4.5 to 4.9% aluminum, 2.5 to 3% manganese, 0.7 to 1% chromium and copper.

1 Claims, No Drawings NONMAGNETIC COPPER-BASED ALLOY The present invention relates to alloys utilized in apparatus for magnetic tape recording and playback as the material of nonmagnetic shims or spacers in the gaps of magnetic heads, as well as that for making springs.

For the purpose use is made of beryllium bronze of the following composition (in weight percent):

Be 1.9 to 2.2

Ni-0.2 to 0.5

Cu-all the rest.

However, the use of said bronze is hampered by its being highly toxic and expensive material; thus, the maximum permissible beryllium concentration in the air of working rooms makes up but 0.00] mg./cu.m. In practical work with beryllium bronze this concentration limit is usually exceeded which results in heavy poisoning of the working personnel.

Another alloy is employed for nonmagnetic shims or as a material for springs, its composition being as follows (in weight percent):

Nil2.2 to 14.8

Al2.5 to 3.5 Mn2.5 to 3.5 Cr-l to 2 Cu-all the rest Both the quality and sound track capacity of a magnetic tape recording depend upon the thickness and quality of the nonmagnetic shims or spacers of magnetic heads, their thickness being specified to lie within 1.5 to 2 microns. The quality of the shims is checked visually under microscope.

The above-mentioned alloy being nontoxic one, meets all the requisitions specified for the materials of nonmagnetic shims, but is silvery-colored close to that of the material of magnetic heads which fact interferes with the visual appreciation of the quality of shims under microscope.

The silvery coloration of the above alloy does not impede it to be used as a material for making springs. However, high nickel content (up to 14.8 percent) of the alloy makes it too expensive which restricts its application for making springs.

it is an object of the present invention to provide a cheaper nonmagnetic copper-based alloy which would possess high mechanical properties and whose color be distinctly different from that of the magnetic materials the sound-recording heads are made from.

According to the present invention a nonmagnetic copperbased alloy is disclosed, said alloy incorporating nickel, aluminum, manganese, chromium. A salient feature of that alloy is the fact that the alloy components are taken in the following weight percentage:

Ni-4.5 to 4.9

Al4.5 to 4.9

Mn2.5 to 3.0

Cr-0.7 to l Cu-all the rest.

The resulting alloy is yellow-colored, whereby it is readily discernible from the material of the heads and allows of easy quality checking of the nonmagnetic shims under microscope.

Reduction of the nickel content of the alloy down to 4.5 4.9 weight percent makes the alloy still cheaper and, consequently, contributes to its being widely employed as a material for making springs.

For better understanding of the subject of the invention given below are some examples of possible compositions of the herein-disclosed alloy and the description of the properties thereof.

Example I The alloy may be of the following composition (in weight percent):

Cuall the rest.

Example 2 The alloy may be of the following composition (in weight percent):

Cuall the rest.

Example 3 Mechanical Unit of After L istic L 5 cold tempering at 850 C. rolling at 400 C. within 2 hrs.

1. Vickers hardness number kg./mm.* 87 222 295 2. Tensile strength kg./mm. 47 78 ll? 3. Percentage elongation percent 43 8 4 The herein-proposed alloy is a nonmagnetic one and possess high plasticity which allows of obtaining quality foil up to 2 me. thick.

Application of the present alloy as a material for shims in magnetic heads improves the frequency response of the apparatus, increases the playback amplitude and diminishes its scatter.

Testing of the present alloy in magnetic recording and playback apparatus has shown the endurance of the alloy to approximate that of the magnetic material of sound-recording heads. This precludes the formation of depressions or pittings in the nonmagnetic shim which, in turn, contributes to an increased service life of the magnetic head involved.

What we claim is:

1. A nonmagnetic copper-based alloy, consisting of Ni-4.5 to 4.9 percent Al-4.5 to 4.9 percent Mn2.5 to 3.0 percent Cr-0.7 to 1 percent Cu--balance. 

